TC tornadoes are often spawned by unusually small storm cells
that may not appear particularly dangerous on weather radars,
especially if the cells are located more than about 60 miles
from the radar. In addition, these small storms often tend to
produce little or no lightning or thunder, and may not look very
threatening visually to the average person. Furthermore, the
tornadoes are often obscured by rain, and the storm cells
spawning them may move rapidly, leaving little time to take
evasive action once the threat has been perceived.
( McCaul et al. 1996,
Spratt et al. 1997).